package PerlIO::via::PrepareCP1251;

# $Id$
# ABSTRACT: prepare unicode stream to be encoded as cp1251

use 5.010;
use strict;
use warnings;
use autodie;
use utf8;
use charnames ':full';

use Unicode::Normalize;
use Data::Dumper;


our $VERSION = 0.02;




my %cmap = (

    # Kazakh

    "\x{04D8}" => "\x{0410}",       # SCHWA
    "\x{04D9}" => "\x{0430}",
    "\x{0492}" => "\x{0413}",       # GHE WITH STROKE
    "\x{0493}" => "\x{0433}",
    "\x{04A2}" => "\x{041D}",       # EN WITH DESCENDER
    "\x{04A3}" => "\x{043D}",
    "\x{04AE}" => "\x{0423}",       # STRAIGHT U
    "\x{04AF}" => "\x{0443}",
    "\x{04B0}" => "\x{0423}",       # STRAIGHT U WITH STROKE
    "\x{04B1}" => "\x{0443}",
    "\x{04BA}" => "\x{0425}",       # SHHA
    "\x{04BB}" => "\x{0445}",
    "\x{049A}" => "\x{041A}",       # KA WITH DESCENDER
    "\x{049B}" => "\x{043A}",
    "\x{04E8}" => "\x{041E}",       # BARRED O
    "\x{04E9}" => "\x{043E}",
);

my %codepage;

while ( <DATA> ) {
    next unless my ( $code, $ucode ) = m{ 0x ([0-9A-F]{2}) \s+ 0x ([0-9A-F]{4}) }xms;
    $codepage{ chr hex $ucode } = chr hex $code;
}


# remove diacritics
for my $codepoint ( 0x000 .. 0x2FFF ) {
    my $chr = chr $codepoint;
    next if exists $codepage{$chr};
    next if exists $cmap{$chr};

    my $nfd = substr NFD( $chr ), 0, 1;
    next unless exists $codepage{$nfd};

    $cmap{$chr} = $nfd;
}

sub _convert_symbol {
    my ($char) = @_;
    if ( my $name = charnames::viacode(ord $char) ) {
        return "\\N{$name}";
    }
    return sprintf '\x{%04x}', ord $char;
}



# based on PerlIO::via::QuotedPrint example

=head1 PerlIO::via interface

=head2 PUSHED
    
    Initialize layer

=cut

sub PUSHED {
    my ( $class ) = @_;
    return bless \*PUSHED, $class;
};


=head2 WRITE

    Filter text

=cut

sub WRITE {
    my ( undef, $line, $handle ) = @_;
    utf8::decode( $line ); # need to promote things back to UTF8
    my $out = join q{},
        map { $cmap{$_} // ( exists $codepage{$_} ? $_ : _convert_symbol($_) ) }
        split m//, $line;
    # utf8::downgrade($x);
    return ( print {$handle} $out ) ? length($line) : -1;
}

1;


__DATA__
#
#    Name:     cp1251 to Unicode table
#    Unicode version: 2.0
#    Table version: 2.01
#    Table format:  Format A
#    Date:          04/15/98
#
#    Contact:       Shawn.Steele@microsoft.com
#
#    General notes: none
#
#    Format: Three tab-separated columns
#        Column #1 is the cp1251 code (in hex)
#        Column #2 is the Unicode (in hex as 0xXXXX)
#        Column #3 is the Unicode name (follows a comment sign, '#')
#
#    The entries are in cp1251 order
#
0x00    0x0000  #NULL
0x01    0x0001  #START OF HEADING
0x02    0x0002  #START OF TEXT
0x03    0x0003  #END OF TEXT
0x04    0x0004  #END OF TRANSMISSION
0x05    0x0005  #ENQUIRY
0x06    0x0006  #ACKNOWLEDGE
0x07    0x0007  #BELL
0x08    0x0008  #BACKSPACE
0x09    0x0009  #HORIZONTAL TABULATION
0x0A    0x000A  #LINE FEED
0x0B    0x000B  #VERTICAL TABULATION
0x0C    0x000C  #FORM FEED
0x0D    0x000D  #CARRIAGE RETURN
0x0E    0x000E  #SHIFT OUT
0x0F    0x000F  #SHIFT IN
0x10    0x0010  #DATA LINK ESCAPE
0x11    0x0011  #DEVICE CONTROL ONE
0x12    0x0012  #DEVICE CONTROL TWO
0x13    0x0013  #DEVICE CONTROL THREE
0x14    0x0014  #DEVICE CONTROL FOUR
0x15    0x0015  #NEGATIVE ACKNOWLEDGE
0x16    0x0016  #SYNCHRONOUS IDLE
0x17    0x0017  #END OF TRANSMISSION BLOCK
0x18    0x0018  #CANCEL
0x19    0x0019  #END OF MEDIUM
0x1A    0x001A  #SUBSTITUTE
0x1B    0x001B  #ESCAPE
0x1C    0x001C  #FILE SEPARATOR
0x1D    0x001D  #GROUP SEPARATOR
0x1E    0x001E  #RECORD SEPARATOR
0x1F    0x001F  #UNIT SEPARATOR
0x20    0x0020  #SPACE
0x21    0x0021  #EXCLAMATION MARK
0x22    0x0022  #QUOTATION MARK
0x23    0x0023  #NUMBER SIGN
0x24    0x0024  #DOLLAR SIGN
0x25    0x0025  #PERCENT SIGN
0x26    0x0026  #AMPERSAND
0x27    0x0027  #APOSTROPHE
0x28    0x0028  #LEFT PARENTHESIS
0x29    0x0029  #RIGHT PARENTHESIS
0x2A    0x002A  #ASTERISK
0x2B    0x002B  #PLUS SIGN
0x2C    0x002C  #COMMA
0x2D    0x002D  #HYPHEN-MINUS
0x2E    0x002E  #FULL STOP
0x2F    0x002F  #SOLIDUS
0x30    0x0030  #DIGIT ZERO
0x31    0x0031  #DIGIT ONE
0x32    0x0032  #DIGIT TWO
0x33    0x0033  #DIGIT THREE
0x34    0x0034  #DIGIT FOUR
0x35    0x0035  #DIGIT FIVE
0x36    0x0036  #DIGIT SIX
0x37    0x0037  #DIGIT SEVEN
0x38    0x0038  #DIGIT EIGHT
0x39    0x0039  #DIGIT NINE
0x3A    0x003A  #COLON
0x3B    0x003B  #SEMICOLON
0x3C    0x003C  #LESS-THAN SIGN
0x3D    0x003D  #EQUALS SIGN
0x3E    0x003E  #GREATER-THAN SIGN
0x3F    0x003F  #QUESTION MARK
0x40    0x0040  #COMMERCIAL AT
0x41    0x0041  #LATIN CAPITAL LETTER A
0x42    0x0042  #LATIN CAPITAL LETTER B
0x43    0x0043  #LATIN CAPITAL LETTER C
0x44    0x0044  #LATIN CAPITAL LETTER D
0x45    0x0045  #LATIN CAPITAL LETTER E
0x46    0x0046  #LATIN CAPITAL LETTER F
0x47    0x0047  #LATIN CAPITAL LETTER G
0x48    0x0048  #LATIN CAPITAL LETTER H
0x49    0x0049  #LATIN CAPITAL LETTER I
0x4A    0x004A  #LATIN CAPITAL LETTER J
0x4B    0x004B  #LATIN CAPITAL LETTER K
0x4C    0x004C  #LATIN CAPITAL LETTER L
0x4D    0x004D  #LATIN CAPITAL LETTER M
0x4E    0x004E  #LATIN CAPITAL LETTER N
0x4F    0x004F  #LATIN CAPITAL LETTER O
0x50    0x0050  #LATIN CAPITAL LETTER P
0x51    0x0051  #LATIN CAPITAL LETTER Q
0x52    0x0052  #LATIN CAPITAL LETTER R
0x53    0x0053  #LATIN CAPITAL LETTER S
0x54    0x0054  #LATIN CAPITAL LETTER T
0x55    0x0055  #LATIN CAPITAL LETTER U
0x56    0x0056  #LATIN CAPITAL LETTER V
0x57    0x0057  #LATIN CAPITAL LETTER W
0x58    0x0058  #LATIN CAPITAL LETTER X
0x59    0x0059  #LATIN CAPITAL LETTER Y
0x5A    0x005A  #LATIN CAPITAL LETTER Z
0x5B    0x005B  #LEFT SQUARE BRACKET
0x5C    0x005C  #REVERSE SOLIDUS
0x5D    0x005D  #RIGHT SQUARE BRACKET
0x5E    0x005E  #CIRCUMFLEX ACCENT
0x5F    0x005F  #LOW LINE
0x60    0x0060  #GRAVE ACCENT
0x61    0x0061  #LATIN SMALL LETTER A
0x62    0x0062  #LATIN SMALL LETTER B
0x63    0x0063  #LATIN SMALL LETTER C
0x64    0x0064  #LATIN SMALL LETTER D
0x65    0x0065  #LATIN SMALL LETTER E
0x66    0x0066  #LATIN SMALL LETTER F
0x67    0x0067  #LATIN SMALL LETTER G
0x68    0x0068  #LATIN SMALL LETTER H
0x69    0x0069  #LATIN SMALL LETTER I
0x6A    0x006A  #LATIN SMALL LETTER J
0x6B    0x006B  #LATIN SMALL LETTER K
0x6C    0x006C  #LATIN SMALL LETTER L
0x6D    0x006D  #LATIN SMALL LETTER M
0x6E    0x006E  #LATIN SMALL LETTER N
0x6F    0x006F  #LATIN SMALL LETTER O
0x70    0x0070  #LATIN SMALL LETTER P
0x71    0x0071  #LATIN SMALL LETTER Q
0x72    0x0072  #LATIN SMALL LETTER R
0x73    0x0073  #LATIN SMALL LETTER S
0x74    0x0074  #LATIN SMALL LETTER T
0x75    0x0075  #LATIN SMALL LETTER U
0x76    0x0076  #LATIN SMALL LETTER V
0x77    0x0077  #LATIN SMALL LETTER W
0x78    0x0078  #LATIN SMALL LETTER X
0x79    0x0079  #LATIN SMALL LETTER Y
0x7A    0x007A  #LATIN SMALL LETTER Z
0x7B    0x007B  #LEFT CURLY BRACKET
0x7C    0x007C  #VERTICAL LINE
0x7D    0x007D  #RIGHT CURLY BRACKET
0x7E    0x007E  #TILDE
0x7F    0x007F  #DELETE
0x80    0x0402  #CYRILLIC CAPITAL LETTER DJE
0x81    0x0403  #CYRILLIC CAPITAL LETTER GJE
0x82    0x201A  #SINGLE LOW-9 QUOTATION MARK
0x83    0x0453  #CYRILLIC SMALL LETTER GJE
0x84    0x201E  #DOUBLE LOW-9 QUOTATION MARK
0x85    0x2026  #HORIZONTAL ELLIPSIS
0x86    0x2020  #DAGGER
0x87    0x2021  #DOUBLE DAGGER
0x88    0x20AC  #EURO SIGN
0x89    0x2030  #PER MILLE SIGN
0x8A    0x0409  #CYRILLIC CAPITAL LETTER LJE
0x8B    0x2039  #SINGLE LEFT-POINTING ANGLE QUOTATION MARK
0x8C    0x040A  #CYRILLIC CAPITAL LETTER NJE
0x8D    0x040C  #CYRILLIC CAPITAL LETTER KJE
0x8E    0x040B  #CYRILLIC CAPITAL LETTER TSHE
0x8F    0x040F  #CYRILLIC CAPITAL LETTER DZHE
0x90    0x0452  #CYRILLIC SMALL LETTER DJE
0x91    0x2018  #LEFT SINGLE QUOTATION MARK
0x92    0x2019  #RIGHT SINGLE QUOTATION MARK
0x93    0x201C  #LEFT DOUBLE QUOTATION MARK
0x94    0x201D  #RIGHT DOUBLE QUOTATION MARK
0x95    0x2022  #BULLET
0x96    0x2013  #EN DASH
0x97    0x2014  #EM DASH
0x98            #UNDEFINED
0x99    0x2122  #TRADE MARK SIGN
0x9A    0x0459  #CYRILLIC SMALL LETTER LJE
0x9B    0x203A  #SINGLE RIGHT-POINTING ANGLE QUOTATION MARK
0x9C    0x045A  #CYRILLIC SMALL LETTER NJE
0x9D    0x045C  #CYRILLIC SMALL LETTER KJE
0x9E    0x045B  #CYRILLIC SMALL LETTER TSHE
0x9F    0x045F  #CYRILLIC SMALL LETTER DZHE
0xA0    0x00A0  #NO-BREAK SPACE
0xA1    0x040E  #CYRILLIC CAPITAL LETTER SHORT U
0xA2    0x045E  #CYRILLIC SMALL LETTER SHORT U
0xA3    0x0408  #CYRILLIC CAPITAL LETTER JE
0xA4    0x00A4  #CURRENCY SIGN
0xA5    0x0490  #CYRILLIC CAPITAL LETTER GHE WITH UPTURN
0xA6    0x00A6  #BROKEN BAR
0xA7    0x00A7  #SECTION SIGN
0xA8    0x0401  #CYRILLIC CAPITAL LETTER IO
0xA9    0x00A9  #COPYRIGHT SIGN
0xAA    0x0404  #CYRILLIC CAPITAL LETTER UKRAINIAN IE
0xAB    0x00AB  #LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
0xAC    0x00AC  #NOT SIGN
0xAD    0x00AD  #SOFT HYPHEN
0xAE    0x00AE  #REGISTERED SIGN
0xAF    0x0407  #CYRILLIC CAPITAL LETTER YI
0xB0    0x00B0  #DEGREE SIGN
0xB1    0x00B1  #PLUS-MINUS SIGN
0xB2    0x0406  #CYRILLIC CAPITAL LETTER BYELORUSSIAN-UKRAINIAN I
0xB3    0x0456  #CYRILLIC SMALL LETTER BYELORUSSIAN-UKRAINIAN I
0xB4    0x0491  #CYRILLIC SMALL LETTER GHE WITH UPTURN
0xB5    0x00B5  #MICRO SIGN
0xB6    0x00B6  #PILCROW SIGN
0xB7    0x00B7  #MIDDLE DOT
0xB8    0x0451  #CYRILLIC SMALL LETTER IO
0xB9    0x2116  #NUMERO SIGN
0xBA    0x0454  #CYRILLIC SMALL LETTER UKRAINIAN IE
0xBB    0x00BB  #RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
0xBC    0x0458  #CYRILLIC SMALL LETTER JE
0xBD    0x0405  #CYRILLIC CAPITAL LETTER DZE
0xBE    0x0455  #CYRILLIC SMALL LETTER DZE
0xBF    0x0457  #CYRILLIC SMALL LETTER YI
0xC0    0x0410  #CYRILLIC CAPITAL LETTER A
0xC1    0x0411  #CYRILLIC CAPITAL LETTER BE
0xC2    0x0412  #CYRILLIC CAPITAL LETTER VE
0xC3    0x0413  #CYRILLIC CAPITAL LETTER GHE
0xC4    0x0414  #CYRILLIC CAPITAL LETTER DE
0xC5    0x0415  #CYRILLIC CAPITAL LETTER IE
0xC6    0x0416  #CYRILLIC CAPITAL LETTER ZHE
0xC7    0x0417  #CYRILLIC CAPITAL LETTER ZE
0xC8    0x0418  #CYRILLIC CAPITAL LETTER I
0xC9    0x0419  #CYRILLIC CAPITAL LETTER SHORT I
0xCA    0x041A  #CYRILLIC CAPITAL LETTER KA
0xCB    0x041B  #CYRILLIC CAPITAL LETTER EL
0xCC    0x041C  #CYRILLIC CAPITAL LETTER EM
0xCD    0x041D  #CYRILLIC CAPITAL LETTER EN
0xCE    0x041E  #CYRILLIC CAPITAL LETTER O
0xCF    0x041F  #CYRILLIC CAPITAL LETTER PE
0xD0    0x0420  #CYRILLIC CAPITAL LETTER ER
0xD1    0x0421  #CYRILLIC CAPITAL LETTER ES
0xD2    0x0422  #CYRILLIC CAPITAL LETTER TE
0xD3    0x0423  #CYRILLIC CAPITAL LETTER U
0xD4    0x0424  #CYRILLIC CAPITAL LETTER EF
0xD5    0x0425  #CYRILLIC CAPITAL LETTER HA
0xD6    0x0426  #CYRILLIC CAPITAL LETTER TSE
0xD7    0x0427  #CYRILLIC CAPITAL LETTER CHE
0xD8    0x0428  #CYRILLIC CAPITAL LETTER SHA
0xD9    0x0429  #CYRILLIC CAPITAL LETTER SHCHA
0xDA    0x042A  #CYRILLIC CAPITAL LETTER HARD SIGN
0xDB    0x042B  #CYRILLIC CAPITAL LETTER YERU
0xDC    0x042C  #CYRILLIC CAPITAL LETTER SOFT SIGN
0xDD    0x042D  #CYRILLIC CAPITAL LETTER E
0xDE    0x042E  #CYRILLIC CAPITAL LETTER YU
0xDF    0x042F  #CYRILLIC CAPITAL LETTER YA
0xE0    0x0430  #CYRILLIC SMALL LETTER A
0xE1    0x0431  #CYRILLIC SMALL LETTER BE
0xE2    0x0432  #CYRILLIC SMALL LETTER VE
0xE3    0x0433  #CYRILLIC SMALL LETTER GHE
0xE4    0x0434  #CYRILLIC SMALL LETTER DE
0xE5    0x0435  #CYRILLIC SMALL LETTER IE
0xE6    0x0436  #CYRILLIC SMALL LETTER ZHE
0xE7    0x0437  #CYRILLIC SMALL LETTER ZE
0xE8    0x0438  #CYRILLIC SMALL LETTER I
0xE9    0x0439  #CYRILLIC SMALL LETTER SHORT I
0xEA    0x043A  #CYRILLIC SMALL LETTER KA
0xEB    0x043B  #CYRILLIC SMALL LETTER EL
0xEC    0x043C  #CYRILLIC SMALL LETTER EM
0xED    0x043D  #CYRILLIC SMALL LETTER EN
0xEE    0x043E  #CYRILLIC SMALL LETTER O
0xEF    0x043F  #CYRILLIC SMALL LETTER PE
0xF0    0x0440  #CYRILLIC SMALL LETTER ER
0xF1    0x0441  #CYRILLIC SMALL LETTER ES
0xF2    0x0442  #CYRILLIC SMALL LETTER TE
0xF3    0x0443  #CYRILLIC SMALL LETTER U
0xF4    0x0444  #CYRILLIC SMALL LETTER EF
0xF5    0x0445  #CYRILLIC SMALL LETTER HA
0xF6    0x0446  #CYRILLIC SMALL LETTER TSE
0xF7    0x0447  #CYRILLIC SMALL LETTER CHE
0xF8    0x0448  #CYRILLIC SMALL LETTER SHA
0xF9    0x0449  #CYRILLIC SMALL LETTER SHCHA
0xFA    0x044A  #CYRILLIC SMALL LETTER HARD SIGN
0xFB    0x044B  #CYRILLIC SMALL LETTER YERU
0xFC    0x044C  #CYRILLIC SMALL LETTER SOFT SIGN
0xFD    0x044D  #CYRILLIC SMALL LETTER E
0xFE    0x044E  #CYRILLIC SMALL LETTER YU
0xFF    0x044F  #CYRILLIC SMALL LETTER YA

